Traffic signal



Aug. 17, 1943. E. F. HUBACKER TRAFFIC S IGNAL 2 Sheets-Sheet l Filed Dec. 5, 1941 Patented Aug. 17, 1943 Earl F. Hubackenllighland Park, Mich., assignor to a partnership consisting of J. Stuart Bicknell, Mark H. Bicknell, Haroldiiianchett, and W. James lson,lClare, Mich.

Application December 5, 1941, Serial No. 421,722

12 Claims.

This invention relates to electric t-railic signals and particularly to a new andimproved mechanism for controlling th operation thereof.

A principal object of the invention is toprovide a. new and improved iorm of electric trafiic signal andcontrols therefor. Another object of the invention is to provide an electric trafiic signal which is adapted to utilize a battery as the sourced-current.

Another object of the invention is tdprovide a new, improved and more simplified circuit and control -means therefor for an electric traflic signal.

Another object of the invention is to provide an electric traffic signal with a simplified-and very inexpensive means of adjustingthe timing of the lights in one direction relativ to the timingoi the lights in the other direction.

Another object of theinvention is to provide a new and improved-electric traffic signalcontrol which is very simple in construction, very dependable in operation, and which is particularly adapted'for'use'with a-battery asa source'of current.

Other objects and-advantages oi the invention will be apparent from a consideration of the following specification taken in conjunction with the accompanying drawings, of -which-thereare two sheetsand wherein:

Fig. l is a-- diagrammatic illustration of an electric trafiic control mechanism embodying the invention;

Fig. 2-isa plan view-of a thermostaticswitch useful in practising the invention;

, Fig. 3 is a diagrammatic-illustration of the electrical interlock between the sets of lights; and

Fig. 4 isa diagrammatic illustration of another embodiment of theinvention.

Referring now to Fig.- 1, there'is diagrammatieally illustrated an electric trairic control mechanism embodying the invention and which in general comprises a seriesoi red lights markedRE, RS, RW, and RN, and which are adapted to face in four directionsat a trafiic intersection,

the letter Rindicating that thelamp orllight is letter indicating that the light, faces east, south, west, or north, as the-case maybe.

The lights marked RS, RN, GE, and GW are all connected to the electrical conductor I0, and each of these lamps is grounded so that when the circuit is closed all of the lamps connected to the conductor in will be actuated .1or lit. The lamps marked RE, :RW, GS and .GN are .connected to the conductor l2 and are .alLgrounded so that when the circuit, of whichtheconductor 12 forms a part, is closed, the lamps connected tothe conductor IZ-Willb actuated or lit. ,Means as 'hereinafter described are provided for alternately lighting the lamps connected .to the circults i0 and i2.

The lamps areadaptedto be arranged orsupported in a suitable housing which is adapted to lac-arranged at -a-traffic intersection forcontrolling the flow of trafiicthrough the intersection, and,-as in the case-of aconventional traific signal, when thegreenlightsiacing north and south and the red lights facing east and west, for example, are actuated, the .north and .south bound traflic is allowed tomove while the east and west bound traific is halted. When the lights change, the north and south redlights .areactuated to halt the north-andsout-h trafllc,,while the east and west'green lights .are actuated to permit movementoi the east and .westvtraflic.

The conductors ill and H are connected through the control mechanismv hereinafter. described to a source of current, such asca battery indicated at ld, throughamanually controlled switch indicated at 16. The battery I4 is grounded, and when the switch l6 isclosed the control mechanism hereinafter described is adapted to alternately operate the sets of lights as previously indicated. Thelights, .as .well as the mechanism previously indicated, are arranged-in a suitable housing, and whena battery is used it will b apparent that the-housing may be of a portable nature, that is, the traffiic control unit including its source-of power will be self-contained and may be arranged foroperation in temporary locations or in locations where a source of power is not available.

The control mechanism as illustrated in Fig. 1 comprises thermostatically controlled switches indicated generally at 8 and '26. An electric conductor 22 connected'tc one side of the battery It whenthe switch i5 is closed is-connected to one end i i of a resistance 25,-the other end -28 of which is connected to the movable element 30 of a thermostatic switch '32 which is connected through a double switch '34, when the same is closed, to the conductor as. The switch 32 is normally closed, and the switch 34 is controlled by a magnetic relay, the 'coil 85 of which is grounded at one end and connected through the switch 32 and resistance 28 to the conductor 22 at the other end. V

The movable'arm 38 of the relay has 0011-. nected tofitthe movable contacts of the switch and when the switches i6 and 32 are'closed, the coil 36 is energized and will hold the switch 3?. closed, thereby completing the circuit from the battery it through switch it, conductor 22,

resistance 2%, switch 32. switch B l, conductor), i A variableresistance i8 is arranged in parallel to the resistance 26 for the purpose hereinafter described' and the lamps. connected thereto.

' contact'of the switch 32 and the stationary pivot e l-and will cause the movable element 33 of the switch lii to move and open the switch 32, there- Amber lights All and AW are connected tocon- 7 ductor 62, which forms a part of the circuit for the amber lights, and which is connected to one;

ranged as illustratedin Fig; 1, current is flowing in the circuit whichcontrolsthe BS, EN, GE, and GW lights and. also through the, coil 36 of the magnetic relay. Resistance 23 forms a heating element or therm'ostaticmeans ior actuating the movable contact 39 of switch 32 and also the movable element of switch 68. 'While; the

switch 32 is closed, the heating element is adapted to actuate the movable element 58 of the switch and'close the same,.thereby turning on the amberlightsAE and AW. After a pre I determined time interval the heating element 26 isadapted to actuate-movable element 38 of the switch=32 to. open the same, which breaks the circuitthrough the'magnetic relay thereby opening the switches and t l and breaking the circuits'through the-red, green and amber lights connectedv to theconductors l5 and 42;

A somewhat diagrammatic illustration of a thermostatic switch whichmay be employed is illustrated in Fig. 2, and may consistof a base E i-upon which the various elements are mounted.

"The conductor 22 maybe connected to a binding post 56 to which the end '24 of the resistance 2% is connected, the other. endZ-S ofthe resistance being fastenedto an arm 53 which is mounted on a spring leaf 6%, which in turn is mounted upon the block 62. The movable element 3i] of theswitch32 may comprise a spring leai and be mounted upon. stationary pivot (is and movable pivot ESiormed .on the member 58. The switche's 32 and 28 are illustrated in Fig. 2 in the same position as in Fig. l. 1 I i. The movable element 5% of the switch is may comprise a spring leaf and be mounted between the movable pivot and a stationary pivot 68 and, as illustrated, the contact carried by the movable element Siloi the switch 48 ispositioned against a stop it. The flow of current through .the resistance 26 will cause the same to lengthen,

thereby permitting the movable pivot 65 to move in a clockwise direction with regard to the block ei'under thebias of the spring 63. After the current has been flowing through the resistance 26 for a predetermined time interval, for exampic .25 seconds the movable pivot 65 will move sufliciently to cause the movable element 58 of the switch 58 to engage the stationary contact thereof. This will'occur when themovable ele-' ment 56 moves to the other side of the line formed by the stop it! and. the stationary pivot 63. When the switch d8 closes, theamber lights will comeon as previously described. After a further time interval, forexample five seconds,

the'movable' pivot 66. willfhave moved to' the other side of a line formed by the stationary by breaking the circuit through the lamps connected to the conductors it and 42 and the cir- "cuit-througn the relay fiii as previously described.

' The variable resistance 28 in. parallel with the heater element or resistance 25 provides for shunting current. around. the resistance 26 and thereby controls the heating time thereof. As the resistance 58 is increased, the time required for the element 2?} to heat up and actuate the switches 32 and .43 will be decreased, whileas the resistance it is decreased the time e1ementrequired; for the resistance to. actuate the switches 32 and 58 will be increasedl Ihus, by

adjustment of the resistance-46, the time interval.

that the lamps connected to the conductorsii! and 42 are energized maybe variedwithin certain limitations as hereinaiter set forth.

The amber lights AS and AN are connected to 1 a conductor 12 and are adapted to be 'energized with andatth e endof the period of energization of the green lamps GN and GS. The control mechanism for the circuit through the lamps con- ;nectedto the conductors IZand lQ isthesanie as that for thele psjconnectedto the conductors it and 42-, and toindicate the corresponding parts of the control means for the conductors}? and [2, the same reference characters employed in connection with the control means for the conductors ii] and .12 aroused with "the prefix-l -addeid thereto. Thus the conductor 22 is connected to one end i 24 ofresistance [2 35, the-other end E28 of which is connected to the movable I element of switch '|32.-,which normal1y is closed. The switch .165 ofth e relay I36 and which controls the circuit through the lamps connected to the conductor I2 is open; as is the switch on which controls the circuitithrough the amber lightconnectedtoithe conductor 12, when the'switches 34 and 44 are closed." .The

switches I32, M8, variable resistance liihrelay 135, and other parts are'iclentieal in construction and operation .to the corresponding parts .of

the control mechanism for the conductors [Band 42, and hence need not be further described-except with reference to themeans which controls the alternate operations of the two circuits,

The movable contacts of; the switches Hand 44 are carried by the element 38, which may comprise a movable arm pivoted at it as illustrated in Fig. a. When the circuit through the coil as is closed as shown in Fig. l .the 'element 33 will be positioned as shown in full lines in Figt fi,

and when the circuit through the coil is brohen, the element 'willamoveto .the'dotted line position indicated inFig. 3. .The movable element I33 ofthe relay. 35 may be pivoted at I15 and have a lug i 38 which "projectsinto an openn as formed in the 'end'of the mi so that when the "coil'35 isenergized "and'the arm 38 positioned as shown in full lines'in Fig. 3, the arm I38.- will "be held in the-positionshown-in full lines in Fig. 3. contacts of the switches I34 and M4, which als0 In this position the movable may be carried by arm 38, will be positioned as illustratedinFig. 1.

When the circuit through the coil 36 is opened, the arm 38 will move to the dotted line position illustrated in Fig. 1 and,since the circuit through the coil of the relay I35 is already closed due to the fact that the switch I32 is closed, the arm I38 will move to the dotted line position shown in Fig. 3. Note that when the arm I38 is in the position shown in dotted lines in Fig. 3 that the arm 38 cannot return from itsdotted line position to its full line position even if the coil 36 is energized, as the end of the arm I38 is in the path of movement of the arm 38. When the circuit through coil 3'5 is opened, arm 38 which carries the movable contacts of switches 34, 44, I34, and I44 will move and open switches 34 and 44 and close switches I34 and I44, and vice versa.

When the circuit through the coil I36 is broken, which happens when the heating element I28 is heated sufficiently to open the switch I32, the arm I38 will move from its dotted line positlon to its full line position in Fig. 3 and permit the arm 33 to returnto its'full line position, thereby closing the switches 34 and 44 simultane ously with the opening of the switches I34 and I44. Thus it will be apparent that when the switches 34 and 44 are open, the switches I34 and I44 will be closed so as to actuate the other set of lights, and when the switches I34 and I44 are open the switches 34 and 44 will be closed. The foregoing providesan interlock between the two circuits which locks one circuit open When the other isclosed.

The variable resistance I43, similar to the variable resistance 40, may be set for varying the time interval that the switches I34 and I44 are closed.

When the switch 32 is opened, thereby also effecting the opening of the switches 34 and 44, the circuit through the resistance 26 is broken. As soon as the resistance 26 cools down, the switch 48 will open and the switch. 32 will close, and the time that the switch I32 is closed after the switches I34 and I44 are closed is of sufficient durationto' permit the switch 32 to close and the: switch 48 to open. Similarly, the switch 32 is closed for a sufiicient time interval to permit the resistance I to cool off and close the switch I32 before the switch 32 is opened. In other words, the switch .32 must be closed for a time interval suflicient to permit the heating element for the switch I32 to cool off and the switch I32 must be closed for a time interval sufiicient to permit the heating element for the switch 32 to cool off. The electrical interlock illustrated in Fig. 3 prevents the closingof the circuit through one set of lights while the circuit through the other set is closed.

- With the foregoing circuit, the minimum time possible is the time required for the thermostatic switches to cool oil and reset. The maximum time may be varied over quite a wide range by adjustment of the resistances 48 and I48;-

The trailic-signal may also be formed to in' clude a beacon light 80 controlled by a manually operated switch 82 and independently of the circuits for the red, green, and amber lights.

In those instances where amber lights are not used, the conductor 42 may be connected to the RE and RW lights and the conductor I2 may be connected to the RS and RN lights thereby providing for turning on the red lights on the same side on which the green lights are on beforethe lights changef? H In the modification illustrated in Fig. 4, use is also made of thermostatically controlled switches, similar to those heretofore illustrated, for actuating the various sets of lights. In this modification, theRS, RN, GE, and GW lamps are all connected to an electrical conductor 2I8, and the RE, RW, GS, and GN lamps are connected toa conductor 2I2. ing the amber east and west lamps, are connected to a conductor 2I4 while the AS and AN amber lights are connected to a conductor 2I8. All of the foregoing lamps are grounded, and are connected through the foregoing conductors and control mechanism therefor to a source of current such. as a battery 218, one side of which is also grounded. The other side of the battery is connected througha manually operated switch 229 to an electrical conductor 222 which is connected to the control mechanism. A manually controlled switch 223 may also be provided to control a circuit through a beacon light 225. The lamps, control mechanism, circuits, and battery 2I8 are all adapted to be mounted in a single housing and comprise a self-contained electric trafiic signal which may be of a portable nature adapted for temporary installation at a trafiic intersection.

In the position in which the control mechanism is illustrated in Fig. 4, the circuit through the lamps connected to the conductor 252 is closed so that the RE, RW, GS, and GN lamps are actuated. The conductor 222 is connected to one end 224 of a heater coil or resistance 225, the other end 228 of which is connected to the movable element 230 of normally closed switch 232, thereby establishing a circuit from the battery through the east and west red lamps and north and south green lamps. The switch 232 also closes the circuit through coil of relay 238, the movable element 238 of which carries the movable contacts of switch 244 which, as illustrated, is closed.

One of thestationary contacts of switch 244 has connected to it the conductor 2"), while the other stationary contact is connected by a conductor 246 to the stationary contact of switch 248 which is normally open. The movable element 250 of switch 248 is also connected to the end 228 of the resistance element 228. After switches 22!] and 232 are closed a predetermined time intervaL'for example 25 seconds, the heater element 226 will cause movable element 256 tomove and close switch 248, thereby establishing a circuit through the conductor 248, switch 244, and. the AS and AN amber lights. After the switch 248 has been closed for a predetermined time interval, for example 5 or 6 seconds, the heater element 226 will actuate the movable element 230 of switch 232 to open the same, thereby breaking the circuit through the RE, RW, GS, and GN lights and through the relay 236, thereby also opening the switch 244 and breaking the circuit through the AS and AN amber lights. A variable resistance 243, similar to the resistance 40, may be provided for varying the flow of current through the resistance 2'25, thereby to vary the timeinterval that the switches 232 and 248 are closed.

Simultaneously with the opening of switches 232 and 244 and the breaking of the circuits through the RE, RW, GS, GN, AS, and AN lamps, the movable element 238 of the relay 236 which carries the movable contacts of the switch 334 will move such contacts and close the switch 334, thereby closing the circuit through resistance 328 and the RS, RN, GE, and GW lamps. The

The AE and AW lamps, be-

' val is desired. 7

attached claims;

issimilartothe resistance 2%, and also has 'avari'alole resistance-349 arranged in'paralle] therewith as illustrated. Afterthe switch beenclosedwfor a suitable time interval, for example 25 seconds, theheaterxel'e rnent resistance @Zdwill actuate movable ele.

resistance 5 rneht ofswitcht it and establishacircuit through the AE,AW amber lights-While the cir unit through the ;:GW, ,RS;'and:RN: lightseis still closed. The thermostatic.switchtlilllpreferably is or the sametype as the's'witch 2%. As'socn as the resistance 226 cools ofi andithe "switchqfil l closes, the circuit through "thefrelay A-tr f c con r a te to b ari es d at a trafiic intersectioncomprising at least' twopsets e ic s n l l ts one o id t I ,p ins-5 .stopfi si l i tif ins n o e e i and. afst --si n ishti cine in ac s dime tion-an'dthe other of said sets comprising a .stopf1si r l l t facing i i ros ection and. a. fies? si al ish v ac ns in sa o e wdime: tion, a source-of electric energy, a circuit include ins normally cl sed he m ta ca yop r ted switch; for electrically connecting one-Of said sets ofv lig hts and said source; the other circuit;in-

' eluding a normally closed thermostatically oper will be clcsedithei'eby opening .switchfilfiif and closing switch 246, therehyopening the -'cir-;

cuit through the GE, GWjLRS, RN,VAE,.andAW lamps and closing the circuit through the: GS; and RV!" lamps. When thelswitch'ztfi resets, the switch 2:38 willopen iinJacc0rd-' ance with the previous description,- will clos'e after the switch 232has been closedapredeter mined time interval. The system asillustrated i in this modification should be designed so that' i the cooling i and resetting peri'od of switchesli and 2558 will; permit the s 33 i? to be closed on whatevert e inter the" 7 "While the inventicnlhas been described with som detail, it is to be understood'thattl1'elde- 'scription is for the purpose of illustration only and isrot definitive-of the limits-of the inventive idi; details or" construction and arranger 're t of parts as will fall within the purviewof 'I'claini: r 7 i -l. A trafiic' control adapted tobeerrang'ed at a traflic intersection comprising a circuit-includilie right is reservedto make suchchan ges ing-a source 'o'f'electric energy, a ncrrna lly'closed the-1 cstaticaliy controlled switch, a relaypon-f trolled switch anda set of signal lights compris-i ing a stop signal light facing'in one direction and afgo signal light facing in a crossdirection, a second circuit including saidsourc'e of electric ener y, a normallyclosed thermostatie cally controlled switch; a relaycontrolled switch, a second 'set' of ignal lights comprising and a go signal tion, and/a elay operatively connected infjlo'ne of said circuits ficr operating said relay controiled' switches which are arranged se that one circuit is opened while the othercircuit is closed.

2. A t;"- c control adapted to be arrangedat a traffic ersection comprising a circuit including a source electric energy, anorinallyclosed: thermostatically controlled switchga relay can trolledswitch and agsetof; signal lig its corn ing stop signal ii'ght'ifacing one direc on and a go signal light facing ina crossdirec tic-n, 'a second circuit including said source: .of electric energy, a normally closed:thermostati-v cally controlledswitch, ai'relay controlled switch and a second set signal lights comprising a stop signal light r main. said cross-direction .ght facing in said onedirfec- Va "trafiiclintersection comprisingat least-two sets ofielectrfici signal lights, one or said setsgc'om 'p'rising aa,stop1signal light facingin eneudi recti'onand a ffgo signal iightiacing in a cross direction andthe lotheraof :said' sets comprising a..st'op signal lightfacinguinisa'id cross direo tion and afffgoVjsignallight facing in said one directioma 1 source ofg-electric-energy, a circuit including la.- normally closed; thermostatically operated svrdtchfor electrically connecting one of said sets of lights and 'saidrsour'ce. the other circuitincludinga normally closed thermostatiically operatedfswitchzfor electrically connecting the other of said sets of lights'randxsaid source, arelayi in one of said -:circuits.and a .switch jin each circuitcontrolled by said relay and arranged so ithat one of said relay controllediswitchesis opened. while-the other is closedtand a relay in the other of said;circnits 'cooperablewithisaid other relayior preventing-theclosing of *therela'y controlled switch :in one of said circuits when the thermostaticallyoperated switch in the other ofsaid circuitsis closed. 5. A trafiic control adapiiedito belarranged at a trafiic intersection comprising at least-two sets 10f electric signal lightsfone of, comprisingxa fstopw signal; ight facingin one direction; and .affgoif signal. li ht facing in :a :css directions-r d thelother ,of'said sets cfirnpiisi ingla ,stopflsignal lighter-facing in said ,cross'die;

creation :an'cl aJfgo, signal light facing ;in{ said one direction, .a'sso'urce 10f electric energy; a aircuit including :ajnorrhallyclosed thermostatically operated switch for electrically gconnectingone .stop signal lightfacing in said cross-direction anda go signal light facingin said one direce tion, arelaycperatively connected in one or" said circuits fcroperatin'g sa'id'relay controlled switches which are arranged so that one-circuitis opened whilexthe, other circuit is closed, and meansto ,prevent'jthe opening of: the relay controlled switch in onexoi saidlcircuitsiwhile the v thermostatically-1 controlled switch lthereinuis closed I 1 2 7 ofzsaid sets? offlights and said source, the other circuit including :a no'rrnfallynclose'd thermostaticallyionerated'switch for electrically connecting the other of said sets of lightsand saidisouitce;

a relay in one of said circuitaaa switch ineach circuit 'controlled by said relay and arranged so that one of 'said'i'relay zcontrolled"iswitche lis V opened while the other is closed 'and means'zto prevent the closing of the relay co'ntrolledswitch in one of said circuits when the 'therniostatically controlled switch in the-other of sai'd'circuits is closed i i I 6. A traffic control 'adapted to jbe arrangedfat a trafiic intersection comprising at least two sets of electric signal lights, onebf said sets coin prising :a stop signalflight facinginone 'direc-' tion and a -go signallight facing in a cross direction and the oth'er of said sets 'comp'risiii'g'- a J ifsto'p signal light jfacing- -in-said cross direction and a .go signal light facingl'in s'aid-one direction, a source of electric" energy',' a circuit switches is; opened saidasets including a normally closed thermostatically operated switch for electrically connecting one ofsaid sets of light and said source, another circuit including a normally closed thermostaticallyoperated switch for electrically connecting the other of said sets of lights and said source, each of said switches being adapted to openafter apredetermined time interval, and means controlled by one of said circuits for alternately opening one of said circuits and closing the other of said circuits.

7, 'A trafiic control adapted to be arranged at a traffic intersection comprising at least two sets of electric signal lights, one of said sets comprising a stop signal light facing in one direction and a go signal light facing in a cross direction and the other of said sets comprising afst'op signal light facing in said cross direction and a go signal light facing in said one direction, asource of electric energy, a circuit including a normally closed thermostatically operated switch for electrically connecting one of said sets of lights and said source, another circuit including a normally closed thermostatically operated switch for electrically connecting the other of said sets of lights and said source, each of said switches being adapted to open aftera predetermined time interval, means controlled by one of said circuits for alternately opening one of said circuits and closing the other of said circuits, and an interlock between said circuits to prevent said means from opening one of said circuits while the thermostaticall controlled switch in said last-mentioned circuit is closed.

8. A traffic control adapted to be arranged at a traflicintersection comprising a set of signal lights, said set comprising a stop signal light facing in one direction and a go signal light facing in a cross direction, a source of electric energy, a circuit operatively connecting said lights and source and including a switch, means responsive to the heat from a resistance in said circuit for opening said switch after a time interval, a'second set of signal lights comprising a stop signal light facing in said cross direction and a go signal light facing in said one direction, a second circuit operatively connecting said second lights and source and including a second switch and means for closing said second switch simultaneously with the opening of said first-rnentioned switch and for preventing the opening of said second switch until the signal lights in said second circuit have been deenerized.

9. A traffic control comprising a first circuit including a source of electric energy, a normally closed thermostatically controlled switch, and a set of signal lights. said set of lights comprising a stop signal light facing in one direction and a go signal light facing in a cross direction, a second circuit including said source of electric energy, a relay controlled switch and a second set of signal lights comprising a stop signal light facing in said cross direction and a go signal light facing in said one direction, and a relay operatively connected in said first circuit for operating said relay controlled switch which is arranged so that its circuit is opened while the first circuit is closed, said thermostatically controlled switch controlling the circuit through said relay and a relay operatively connected in said second circuit for closing said relay controlled switch when said first circuit opens and for preventing the opening of said relay controlled switch with the signal lights in said second circuit have been deenergized.

10. A traflic control comprising a first circuit including a source of electric energy, a normally closed thermostatically controlled switch, and a set of signal lights, said set of lights comprising a stop" signal light facing in one direction and a go signal light facing in a cross direction, a second circuit including said source of electric energy, a relay controlled switch and a second set of signal lights comprising a stop signal light facing in said cross direction and a go signal light facing in said one direction, and a relay operatively connected in said first circuit for operating said relay controlled switch which is arranged so that its circuit is opened while the first circuit is closed, said thermostatically controlled switch controlling the circuit through said relay, a third circuit including said source, a normally opened thermostatically controlled switch, a relay controlled switch and a change signal light, said normally opened thermostatically controlled switch being set to close before said normally closed thermostatically controlled switch in said first circuit opens, and said relay controlled switch being opened by said relay when said normally closed thermostatically controlled switch opens, and a fourth circuit includinga normally opened thermostatically controlled switch, said relay controlled switch of said second circuit and a change" signal light, said last-mentioned normally opened thermostatically controlled switch being set to close a predetermined time interval after said relay controlled switch is closed.

11. A traffic control adapted to be arranged at a traffic intersection comprising at least two sets of electric signal lights, one of said sets comprising a stop signal light facing in onedirection and a go signal light facing in a cross direction and the other of said sets comprising a stop signal light facing in said cross direction and a go signal light facing in said one direction, a source of electrical energy, a first circuit adapted for electrically connecting said source and one of said sets of signal lights and comprising a normally closed thermostatically controlled switch and a relay controlled switch, a second circuit including said relay and controlled by said thermostatically controlled switch and adapted for electrically connecting said relay to said source, a third circuit comprising a normally open thermostatically controlled switch, a switch controlled by said relay and adapted to be opened and closed simultaneously with the relay controlled switch in said first circuit, a change trafiic signal and said source, a fourth circuit adapted for electrically connecting said source and said other of said sets of signal lights comprising a normally closed thermostatically controlled switch and a relay controlled switch, a fifth circuit including said source, said thermostatically controlled switch of said fourth circuit and a relay, and a' sixth circuit including said source, a normally open thermostatically controlled switch, a relay controlled switch and a change traflic signal, said relay controlled switches in said fourth and sixth circuits being controlled by said first-mentioned relay and being adapted to be closed when the relay controlled switches in the first and third circuits are open and to be open when the relay controlled switches in the first and third circuits are closed, said second-mentioned relay being adapted to prevent the opening of the relay controlled 6 V I V V switches in the fourth and sixth circuits when;

the normally closed thermostatically controlled switch in the fourth circuit is closed, said normall-y open thermostatically controlledswitch in the third circuitiheing'set to close when the thermostatically controlled switch in the first circuit is closed and at theendi off its closed period and said'nornia'lly opened thermostaticallycontrolled switch insaid sixthicircuitbeing set to closewhen 'the' thermostatically controlled switch in. the

fourth circuit isclosed; and at the end of its closed'period. 7

12. A traffic control adaptedto be arranged at a creme/intersection comprising. atleast two sets of electric signal" lights, one. of said sets comprising a stop?v signal:lightfacingin one. direc-o tion and a go signal light facing'in-a cross direction and the other of said sets comprising a stop signal light'facing in said cross direction and a go signal light facing in said one direction, a source-of electrical energy, a first circuit adapted for electrically connecting said source andone of'said sets of signal lights and comprising a normallyclosed thermostatically controlledswitch and a 'relay controlled switch, a second circuit including said relay and controlled by saidthermostaticallycontrolled switch and adapted for electrically connecting said relay to said source, a third circuit comprising a normally open thermostatically controlledswitch; a switch 1 Y controlled by said relay and adapted to be opened andoclo'sed simultaneously with'the relay controlled 'switch in said-"first circuit, a change trafiic signal. and said source, a fourthcircuit adapted forelectrically connecting said source and said other of said sets-of signal lightscome prising a normally closed thermostatically con-- trolled switch and a relay controlled switch, a

fifth circuitincluding saidsource, said thermostatically controlled switch of said fourth cir cuit and a relay, and a sixth circuit including said source, a normallyopen thermostatically con.- trolled switch, a relay controlled switch and a change traffic signal, said relay controlled switches in said fourth and sixth circuits being: controlled by said first-mentioned relay-and being adapted to he closed when the relay controlled switches in the first and third circuits are open sixth circuit being set to close when the thermostatically controlled switch inthe fourth circuitis closed and at the end of its closed period, and means for varying the timing of at least one-of said normally opened'and one of said normally v closed thermostatically controlled'switches; o

I EARL F. l-IUBACKERf 

